The invention relates to a procedure for estimating drive speed and position of a permanent magnet rotor of a brushless electrical motor. This procedure is especially suited for use in a drive control circuit. For the procedure, multiple-phase current measurements are used on the motor, whose measurement values, depending on the position estimated, are transformed into a rotor-related d,q-reference frame, i.e. to a direct current vector component and a quadrature current vector component. Together with the estimated (electrical) r.p.m., the direct and quadrature vector components of a current and of a voltage demand are applied as input variables to a mathematical model of the electrical motor. The motor model generates a first output variable and a second output variable, whereby the first output variable corresponds in the d,q reference frame to the d- or direct vector component as well as to a position estimation error, and the second output variable in the d,q reference frame corresponds to the q or quadrature component as well as to a speed estimation error. The two output variables are applied to a tracking controller for estimating and outputting the speed, or the electrical r.p.m., and the position, or the electrical angle. The invention further relates to a position- and/or speed-estimation device to carry out this procedure, a motor modeling module, and a speed tracker according to the respective first parts or preambles of the collateral, independent claims 8, 12 and 15.
For estimation of the position and speed of the permanent magnet rotor in a brushless electrical drive motor, in the Austrian specialized journal “Elektrotechnik und Informationstechnik,” no. 2 for 2000, the article “Controlled Drives”, on pages 103-112, by M. Schrödl and E. Robeischl, provides information about an EMF- or voltage model of the permanent magnet synchronous motor, capable to estimate in real time position and speed information, necessary for example for a drive control, from electrical quantities at higher speed (in the area above about 10% to 20% of nominal speed). The rotor position estimation based on the voltage induced in the stator winding, which does not influence current control. The basic idea of that is to use measurement technique to evaluate the change in the stator flux linkage space vector. By measurement of the current signals, the change in the permanent magnet flux linkage of the permanent magnet rotor is detected.
A system for estimating the drive position and/or speed in a brushless electrical motor, especially a synchronous motor, with a permanent magnet rotor, of about the same type named in the first paragraph, is known, cp. S. M. Abu-Sharkh's and V. Barinberg's article “A new approach to rotor position estimation for a PM brushless motor drive”, Mediterranean Electrotechnical Conference, 1998, pages 1199-1203. According to it, the rotor position and/or speed likewise identified using the EMF—voltage model of the electrical motor. The differentiation of current signals that are necessary for that, but problematical in practice, are avoided by usage of parameter-sensitive low-pass filters, whose time delaying influence is compensated by a proportional-plus-integral tracking controller (PI tracking filter) that is inserted after. The time constant of the low pass filters corresponds the stator time constant of the electrical motor. Using the low pass filters, position and speed estimation errors are weighted.